OSYPKA PACE 203H, Instructions For Use Manual

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PACE 203H – Instructions for Use
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Figure 14: Symbol for Extrasystole
(Premature Ventricular Contraction,
PVC)
For patients with retrograde conduction,
the sensing of a ventricular event, con-
ducted retrograde to the atrium, can lead
to pacemaker mediated tachycardia.
Note
: Pacemaker mediated tachycardia
has been defined as a reentry arrhyth-
mia in which the dual-chamber pace-
maker acts as the antegrade limb of the
tachycardia and the natural pathway acts
as the retrograde limb
3 4
.
PACE 203H prevents pacemaker medi-
ated tachycardia by implementation of a
specific PVC algorithm. The response is
different in case of isolated PVC or the
initial PVC of a series, and subsequent
PVCs.
9.22.5.1 Isolated PVC, or Initial PVC
After detection of a PVC, the PVARP is
extended to 500 ms. Therefore any sen-
sed intrinsic atrial events are not tracked
by the ventricle. After termination of the
extended PVARP, the atrial channel is
‘alert’ and sensing begins again.
3 Furman S, Fisher JD. Endless loop tachy-
cardia in an AV universal (DDD) pace-
maker. Pacing Clin Electrophysiol 1982;
5: 486-489.
4 Den Dulk K, Lindemans FW, Bar FW,
Wellens HJ. Pacemaker related
tachycardias. Pacing Clin Electrophysiol
1982; 5: 476-485.
Despite the extended PVARP, the dur-
ation of the sensing phase, or the width
of the crosstalk sensing window, is set to
at least 350 ms, independent of set basic
rate and A-V Delay. The duration of the
sensing phase may be even longer if the
difference between VA delay and exten-
ded PVARP, i.e.
ms 500 AVD
Rate Basic
1
Phase g sin Sen − − =
(where AVD means the A-V Delay)
reveals a value exceeding 350 ms.
A sensing phase of at least 350 ms
allows atrioventricular synchronization. If
the sensing phase terminates without an
atrial event sensed, PACE 203H delivers
an atrial stimulus - unless a further ven-
tricular extrasystole has been detected.
9.22.5.2 Subsequent PVCs
If a PVC is followed by another PVC
without intermediate atrial sensed or
paced event, the behavior is adapted for
subsequent PVCs, ensuring appropriate
pacing at higher basic rates.
After subsequent PVCs, the PVARP is
extended up to 500 ms, but not
exceeding
ms 20 AVD
Rate Basic
1
PVARP
MAX
− − =
The maximum PVARP is in agreement
with the rules for "abnormal settings"
(see 9.22.7).
After subsequent PVCs, the V-A delay is
calculated to
AVD
Rate Basic
1
Delay VA − =